I have 2 under 2 and a 6.5 year old.
Routine routine routine (with some flexibility) is what keeps us all sane.
DS2 was born in the summer time and we were pretty flexible for the first few weeks when we HAD to be. But as soon as he started back to school, we found our groove.
A few things I found helpful for us:
1) Get the babies up and dressed first thing
2) Do grocery/walmart/target type shopping between 8-10 when everyone is still happy (we drop DS1 off at school and I hit the stores with DS2 in the sling or MT and DD in the front of the cart)
3) Wear the little one as much as is possible so that you can still play with the toddler
4)Do the housework that MUST be done (laundry, dishes) and let the rest go (the bathrooms need not sparkle)
5) Make dinner easy and simple (crockpot stuff, previously prepared frozen stuff, cereals crackers, grapes, easy stuff you don't have to mess around with much) and save the gourmet style cooking for when they are old enough to appreciate it.

I don't know what to tell you about helping the older sibling as my toddler just took everything in stride and still amazes me at how well she does with the baby. It is nothing I have done. It probably doesn't hurt that she's a Daddy's girl atm and he's eating it up.